The safety and efficacy of balanced crystalloid vs. normal saline in non-cardiac surgeries - A systematic review and meta-analysis.

OBJECTIVE: Balanced crystalloid and normal saline are routinely used in clinical anesthesia, but their safety and efficacy in non-cardiac surgeries are still unclear. MATERIALS AND METHODS: PubMed, Embase, Web of Science, Cochrane Library, Wanfang, and CNKI, from January 1980 to March 2023, were searched. Studies comparing balanced crystalloid (BC) with normal saline (NS) during non-cardiac surgeries were included. The primary outcomes were clinical outcomes (acidosis, renal insufficiency, and mortality), and the secondary outcomes were pH value, Na+, Cl- and creatinine levels, and vasopressor requirement. RESULTS: Forty-three RCTs were included in this meta-analysis. Low evidence revealed that the development of acidosis was lower in the BC group than in the NS group (OR: 0.05, 95% CI: 0.01-0.43, I2=80.8%, p=0.00), and no between-group difference exists in renal insufficiency and mortality. At the end of surgery and on postoperative day 1 (POD 1), the pH value was higher, and the levels of Na+ and Cl- were lower in the BC group. No between-group difference exists in creatinine level and vasopressor requirement. CONCLUSIONS: Perioperative balanced crystalloids can maintain the stability of acid-base and electrolyte balance and reduce acidosis compared with saline, but they cannot reduce postoperative renal insufficiency and mortality.

[Insulin-like growth factor-1 alleviates hepatocyte senescence by regulating intranuclear p53-progerin pathway].

To construct cellular senescence model by stimulating primary hepatocytes with hydrogen peroxide (H(2)O(2)). Primary hepatocytes were transfected with p53 siRNA, progerin siRNA or IGF-1 adenovirus vector. The number of SA-ß-Gal stained positive cells and the expression of p53 and progerin were detected. The results showed that p53 siRNA and progerin siRNA had knocked-down the expression of p53 and progerin, and had alleviated the hepatocyte senescence. Transfection of insulin-like growth factor (IGF)-1 adenovirus vector into primary hepatocytes had overexpressed IGF-1, and had alleviated the number of SA-ß-Gal-positive cells. The expression of p53 and progerin was down-regulated in the nucleus, while the expression of p53 was up-regulated in the cytoplasm. The co-precipitation and co-localization of p53 and progerin was decreased in the nuclear region of hepatocytes. IGF-1 overexpression can inhibit intranuclear p53 translocation, alleviate the interaction between p53-progerin, and alleviate hepatocyte senescence.

Oxidative DNA damage is concurrently repaired by base excision repair (BER) and apyrimidinic endonuclease 1 (APE1)-initiated nonhomologous end joining (NHEJ) in cortical neurons.

AIMS: Accumulating studies have suggested that base excision repair (BER) is the major repair pathway of oxidative DNA damage in neurons, and neurons are deficient in other DNA repair pathways, including nucleotide excision repair and homologous recombination repair. However, some studies have demonstrated that neurons could efficiently repair glutamate- and menadione-induced double-strand breaks (DSBs), suggesting that the DSB repair mechanisms might be implicated in neuronal health. In this study, we hypothesized that BER and nonhomologous end joining (NHEJ) work together to repair oxidative DNA damage in neurons. METHODS: Immunohistochemistry and confocal microscopy were employed to examine the colocalization of apyrimidinic endonuclease 1 (APE1), histone variant 2AX (γH2AX) and phosphorylated p53-binding protein (53BP1). APE1 inhibitor and shRNA were respectively applied to suppress APE1 activity and protein expression to determine the correlation of APE1 and DSB formation. The neutral comet assay was used to determine and quantitate the formation of DSB. RESULTS: Both γH2AX and 53BP1 were upregulated and colocalized with APE1 in the nuclei of rat cortical neurons subjected to menadione-induced oxidative insults. Phospho53BP1 foci were efficiently abolished, but γH2AX foci persisted following the suppression of APE1 activity. Comet assays demonstrated that the inhibition of APE1 decreased the DSB formation. CONCLUSIONS: Our results indicate that APE1 can engage the NHEJ mechanism in the repair of oxidative DNA damage in neurons. These findings provide insights into the mechanisms underlying the efficient repair of oxidative DNA damage in neurons despite the high oxidative burden.

MNX1-AS1 accelerates the epithelial-mesenchymal transition in osteosarcoma cells by activating MNX1 as a functional oncogene.

OBJECTIVE: To investigate whether MNX1-AS1 can accelerate epithelial-mesenchymal transition (EMT) of osteosarcoma cells via activating MNX1. PATIENTS AND METHODS: The expression pattern of MNX1-AS1 in osteosarcoma tissues and cell lines was examined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Moreover, the cytoplasmic and nuclear levels of MNX1-AS1 in osteosarcoma cells were also determined. The regulatory effects of MNX1-AS1 on viability, clonality, migratory, and invasive abilities of the osteosarcoma cells were evaluated. The relative levels of MNX1 and EMT-related genes influenced by MNX1-AS1 were detected. The methylation ability in the promoter of the osteosarcoma cells transfected with si-MNX1-AS1 or MNX1-AS1 vector was determined by the whole genome bisulfite sequencing. RESULTS: MNX1-AS1 was upregulated in osteosarcoma tissues and cell lines, which was mainly expressed in the nucleus. The knockdown of MNX1-AS1 markedly attenuated viability, clonality, migratory, and the invasive abilities of the osteosarcoma cells. Besides, the transfection of si-MNX1-AS1 in U2OS and MG63 cells downregulated MNX1 and Snail, and upregulated E-cadherin. The methylation ability increased after the knockdown of MNX1-AS1, while the overexpression of MNX1-AS1 obtained the opposite trends. CONCLUSIONS: MNX1-AS1 mediates EMT of the osteosarcoma cells via activating MNX1, thereafter accelerating the progression of the osteosarcoma.

[Evaluation of curative effect of VNG and VEMP in patients with severe sudden hearing loss].

Objective:To evaluate the relationship between vestibular function and curative effect in patients with severe sudden hearing loss.Method:The vestibular function of 79 patients with severe hearing loss was examined by video-nystagmography (VNG) and vestibular evoked myogenic potential (VEMP).Result:There were significant differences between the two test outcomes (P<0.01) in the severe group (27 cases). The effective rate of both VNG and VEMP normal group was 100%, the effective rate that both VNG and VEMP were abnormal was 41.7%. In the profound severe group (52 cases) there was also a significant difference between the two test results and the therapeutic effect (P<0.01). The effective rate of both VNG and VEMP normal group was 76.9%. The effective rate was 34.6% with both VNG and VEMP abnormal. There was no significant difference between hearing loss degree and curative effect.Conclusion:The VNG and VEMP examinations in patients with severe sudden hearing loss are valuable in evaluating the efficacy. Both VNG and VEMP were abnormal with the worst curative effect.

Improved anchoring nails: design and analysis of resistance ability : Tensile test and finite element analysis (FEA) of improved anchoring nails used in temporomandibular joint (TMJ) disc anchor.

BACKGROUND: Anchorage is one of the most important treatments for severe temporomandibular joint disorder (TMD). Anchoring nails have shown great success in clinical trials; however, they can break under pressure and are difficult to remove. In this study, we aimed to evaluate an improved anchoring nail and its mechanical stability. METHODS: The experiment consisted of two parts: a tensile test and finite element analysis (FEA). First, traditional and improved anchoring nails were implanted into the condylar cortical bone and their tensile strength was measured using a tension meter. Second, a three-dimensional finite element model of the condyles with implants was established and FEA was performed with forces from three different directions. RESULTS: The FEA results showed that the total force of the traditional and improved anchoring nails is 48.2 N and 200 N, respectively. The mean (±s.d.) maximum tensile strength of the traditional anchoring nail with a 3-0 suture was 27.53 ± 5.47 N. For the improved anchoring nail with a 3-0 suture it was 25.89 ± 2.64 N and with a 2-0 suture it was above 50 N. The tensile strengths of the traditional and improved anchoring nails with a 3-0 suture was significantly different (P = 0.033-< 0.05). Furthermore, the difference between the traditional anchoring nail with a 3-0 suture and the improved anchoring nail with a 2-0 suture was also significantly different (P = 0.000-< 0.01). CONCLUSION: The improved anchoring nail, especially when combined with a 2-0 suture, showed better resistance ability compared with the traditional anchoring nail.

[Dairy product intake and influencing factors in residents of Shanghai].

Objective: To understand the dairy product intake in residents of Shanghai, its seasonal changes and the influencing factors. Methods: A group of representative residents was surveyed and followed up in four seasons in Shanghai during 2012-2014. Information of the dairy product intake was collected by food frequency questionnaire. Results: Liquid milk and yogurt were the main dairy products consumed by the residents of Shanghai. The annual dairy product intake rate was 41.8%, and the median of dairy intake of milk was 145.3 g/d, accounting for 48.4% of reference dietary intake value, and only 4.5% of people's diary product intake reached intake reference value. The area specific differences in intake rate of liquid milk, yogurt and total dairy product intake were significant in four seasons and in whole year (P<0.05). The area specific differences in total dairy product intake were significant (P<0.05) in spring, summer and winter. In general, it was shown that dairy product intake in urban area was higher than that in suburban area and in rural area. The data of Shanghai and urban area showed that the total dairy product intake was significant different among four seasons (P<0.05), but no significant difference was observed among four seasons in suburban and rural areas. The logistic regression analysis results showed that people with average household income higher than local average level or higher education levels were more likely to consume dairy products daily. People who reported to have good health status or sleep quality were more likely to drink milk compared to those who have worse health status or sleep quality (P<0.05). Conclusions: Even though dairy product intake rate and volume have been improved in residents in Shanghai, it is still stay at lower level, especially in rural area. To promote consumption of dairy products, it is necessary to control diary product price from macro perspective, and strengthen healthy education about the importance of dairy product intake and guide residents to select suitable dairy products.

The relationship between Muc5ac high secretion and Munc18b upregulation in obese asthma.

OBJECTIVE: Mucus production and hypersecretion are important pathophysiological features of asthma. Airway mucus secretion is more serious in obese asthma. Therefore, it is of great significance to elucidate the mechanism of asthma airway mucus high secretion in improving the control of asthma and the prognosis of obese asthmatic patients. MATERIALS AND METHODS: Obese asthmatic mice model was established to test the airway resistance and mucin secretion by hematoxylin-eosin (HE) staining. Munc18b and Muc5ac expression levels were determined by Western-blotting. Munc18b conditioned knockout mice were adopted to explore the mechanism of Muc5ac high secretion. RESULTS: The mice weight increased in obese asthmatic model accompanied by elevated airway resistance. HE staining showed enhanced mucin secretion, which was correlated to weight and airway resistance. Munc18b and Muc5ac expressions significant upregulated in an obese asthmatic mouse model compared with normal control. Muc5ac expression failed to show elevation in Munc18b conditioned knockout mice. CONCLUSIONS: Muc5ac high secretion was positively correlated with Munc18b upregulation in obese asthma. Munc18b participated in inducing Muc5ac high expression.

Two Distinct Genotypes of Porcine Epidemic Diarrhoea Virus in Vaccinated Pig Flocks in Shandong Province of China, 2012-2015.

As one of the top pork producers in China, Shandong Province suffered frequent outbreaks of porcine epidemic diarrhoea virus (PEDV) on pig farms from January 2012 to July 2015, resulting in significant economic losses. To better understand the prevalence situation, we conducted molecular epidemiological analyses of 38 PEDV strains isolated from 13 cities in Shandong Province. The detection rate of PEDV was 71.2% (146/205) by reverse transcription polymerase chain reaction (RT-PCR). The S genes of the 38 isolated samples were 4146 to 4161 nt in length and shared high levels of sequence identity (93.3-99.6% nt, 92.1-99.4% aa) with those of the 41 reference strains. Among the 38 strains, 31 strains that occupied 12 cities were classed into G3 genotype, while the other seven that only existed in four cities were classed into G2 genotype. In addition, the strains CH-SDLY-2-2014 and CH-SDLY-3-2014 isolated from Linyi were classed into the Gd subgenotype. Notably, there were multiple insertions or deletions in the S genes and several mutations in the neutralizing epitopes of the PEDV S protein. Overall, the results revealed that G2 and G3 are the predominant PEDV genotypes circulating in Shandong Province during 2012-2015, and Gd subgenotype in G3 group had already spread towards northern China in 2014.

Prevention of adhesions in the temporomandibular joint by the use of chitosan membrane in goats.

We evaluated the effects of chitosan membrane, a highly absorbable and viscous material, in the prevention of intra-articular adhesions after anchoring of the disc in the temporomandibular joints (TMJ) of six adult goats (12 joints). To simulate anterior displacement of the disc and TMJ trauma, we cut off the retrodiscal attachment and damaged the surface of the condylar bone, then randomly divided the goats into two groups: the control group (n=2) and the experimental group (n=4). In the experimental group we covered the condylar surfaces on both sides of the animals with chitosan membranes. Those in the control group had operations and no special treatment. We took magnetic resonance images (MRI) of all the animals before the operation and at three and six months postoperatively, and measured the interincisal opening and strength at the same time. We counted the number of adhesions macroscopically, and evaluated the adhesive tissues, cartilage, and subchondral bony changes histologically and immunohistochemically. Measurements of the interincisal opening and strength were significantly better in the experimental group than in the controls (p<0.05). Macroscopic evaluation (using a specific adhesion scoring system) showed a significant difference in the formation of adhesions between the groups (p<0.05). Although MRI showed no significant difference between the groups, the histological and immunohistochemical observations supported the hypothesis that chitosan membrane could prevent intra-articular adhesions. It seems to inhibit the formation of adhesions effectively and promote repair of the cartilage. It may therefore be considered a promising absorbable biomaterial to prevent adhesions after operations on the TMJ.

An instrument for measuring scintillators efficiently based on silicon photomultipliers.

An instrument used for measuring multiple scintillators' light output and energy resolution was developed. The instrument consisted of a light sensor array which was composed of 64 discrete SiPMs (Silicon Photomultipliers), a corresponding individual channel readout electronics system, and a data processing algorithm. A Teflon grid and a large interval between adjacent SiPMs were employed to eliminate the optical cross talk among scintillators. The scintillators' light output was obtained by comparing with a reference sample with known light output. Given the SiPM temperature dependency and the difference among each SiPM, a temperature offset correction algorithm and a non-uniformity correction algorithm were added to the instrument. A positioning algorithm, based on nine points, was designed to evaluate the performance of a scintillator array. Tests were performed to evaluate the instrument's performance. The uniformity of 64 channels for light output measurement was better than 98%, the stability was better than 98% when temperature varied from 15 °C to 40 °C, and the nonlinearity under 511 keV was better than 2%. This instrument was capable of selecting scintillators and evaluating the packaging technology of scintillator arrays with high efficiency and accuracy.

Genetic polymorphisms in metabolic enzymes and susceptibility to anti-tuberculosis drug-induced hepatic injury.

We examined the relationships between N-transacetylase 2 (NAT2), cytochrome P450 (CYP) 2E1 enzyme, glutathione S-transferase M1, T1 (GSTM1/GSTT1) gene polymorphisms, and anti-tuberculosis drug-induced hepatic injury (ADIH). A one-to-one matched case-control study was carried out using clinical data. NAT2, CYP2E1, GSTM1, and GSTT1 polymorphisms were identified in 173 pairs of research subjects. Statistical analysis was performed to determine risk factors of ADIH. The results showed that low body mass index and alcohol consumption were risk factors of ADIH, with odds ratios of 6.852 and 3.203, respectively. The frequencies of NAT2 slow acetylator, CYP2E1 -1259G>C, -1019C>T wild-type, and the GSTM1 null genotype were higher in the case group than in the control group, with odds ratios of 2.260, 2.696, 4.714, and 2.440, respectively. GSTT1 was not found to be related to ADIH. Interactive analysis showed that NAT2 slow acetylator and the GSTM1 null genotype were mutually synergistic, while an antagonistic relationship was observed between the CYP2E1 wild-type genotype and the other 3 genetic types. The risks of hepatic injury were higher after anti-tuberculosis therapy in patients carrying the NAT2 slow acetylator, CYP2E1 -1259G>C, -1019C>T wild-type, and GSTM1 null genotype.

Independent and joint effects of the IL-6 and IL-10 gene polymorphisms in pulmonary tuberculosis among the Chinese Han population.

We investigated the association between interleukin (IL)-6 and IL-10 gene polymorphisms and the susceptibility to pulmonary tuberculosis (PTB). DNA samples were obtained from 191 Han Chinese patients with PTB and 191 healthy control subjects. IL-6 (-572, -174, -597) and IL-10 (-1082, -819) polymorphisms were analyzed using polymerase chain reaction-restriction fragment length polymorphism. The IL-6 -572 C/C and IL-10 -819 T/T genotypes were observed less frequently in the case group than in the control group, with crude odds ratios of 0.591 [95% confidence interval (CI) = 0.381-0.917] and 0.401 (95%CI = 0.257-0.627), respectively. A significant association remained after adjusting for environmental factors in multivariate logistic analysis. The homozygote genotypes of IL-6 -572 and IL-10 -819 had an adjusted OR of 0.565 (95%CI = 0.356-0.898) and 0.341 (95%CI = 0.210-0.553), respectively. These results indicate that the mutant heterozygote IL-10 -1082 A/ G+G/G genotype and the homozygote IL-10 -819 T/T genotype have a combined effect on PTB. These results suggest that the IL-6 -572 C/C and IL-10 -819 T/T genotype polymorphisms are protective factors against PTB.

Clinical characteristics, hospital outcome and prognostic factors of patients with ventilator-related pneumothorax.

BACKGROUND: Mechanical ventilation is a common cause of iatrogenic pneumothorax in intensive care units (ICU). Most of the patients with ventilator-related pneumothorax (VRP) have underlying lung diseases and is associated with increased morbidity and mortality. The prognostic factors of VRP are not clear. The objective of this study was to find the possible prognostic factors. METHODS: Analysis of retrospectively collected data of patients with pneumothorax induced by mechanical ventilation. Data were obtained concerning demographics, acute physiology and chronic health evaluation (APACHE) II score, organ failure, underlying diseases, interval between the start of mechanical ventilation and pneumothorax, arterial blood gas, respiratory parameters and patient outcomes. RESULTS: One hundred and twenty-four patients with VRP were included for analysis. The incidence rate of VRP was 0.4% (124/31,660), and the mortality rate was 77.4%. The patients with VRP had higher hospital mortality rate than that of mechanically ventilated patients without pneumothorax (77.4% vs. 13.7%, P<0.001) or patient with procedure-related pneumothorax (77.4% vs. 29.4%, P<0.001). Most cases of VRP occurred in the early phase of mechanical ventilation, and 8.9% of the patients had a later episode of pneumothorax on the opposite lung. The interval between two episodes of VRP was short, at a median time of 2 days. Cox regression analysis showed that tension pneumothorax (P=0.001), PaO2/FiO2<200 (P=0.002), and APACHE II score (P=0.008) were significantly associated with death. CONCLUSION: VRP patients with tension pneumothorax or PaO2/FiO2<200 had a higher risk of death. APACHE II scores were associated with mortality in the VRP patients with PaO2/FiO2≥200 mmHg.

Stronger in vitro phagocytosis by monocytes-macrophages is indicative of greater pathogen clearance and antibody levels in vivo.

Monocytes-macrophages are crucial players in specific and nonspecific immune responses to protect organisms from invasion of bacteria or viruses. In this study, monocytes in circulation from 2 lines of Silky and Starbro chickens with different disease resistance were separated and cultured in vitro. After identification with acridine orange (AO), Giemsa staining, and CD14 immunostaining, monocytes-macrophages were used for adherence and phagocytosis test. The overall percentages of adherence of Silky monocytes was 1.5 times greater than that of Starbro (P < 0.01), which were 26.85% +/- 8.24% and 18.34% +/- 8.15%, respectively (mean +/- SD). The monocytes-macrophages phagocytic index, phagocytic product, and percentage of phagocytosis in Silkies were greater than in Star-bros, respectively. The difference of phagocytic index was significant (P < 0.05), that is, 3.70 +/- 1.75 and 1.97 +/- 0.31, respectively (mean +/- SD). Then, 20 Silkies were divided into 2 groups according to phagocytic index: high phagocytic index (HPI) group and low phagocytic index (LPI) group, to study the relationship between phagocytic activity in vitro and pathogen clearance. After being challenged against Salmonella Pullorum C79-13, the Silky birds with HPI produced a 3-fold greater level of specific antibodies compared with those with LPI (P < 0.01), 50.21 +/- 6.67 and 16.85 +/- 4.52, respectively (mean +/- SD). In contrast to LPI birds, HPI birds shed less Salmonella Pullorum bacteria (P < 0.05), that is, 168.98 x 10(8) +/- 294.74 x 10(8) compared to 385.40 x 10(8) +/- 399.94 x 10(8) (mean +/- SD), and the shedding peak of Salmonella Pullorum in the test span appeared 4 d earlier. These results indicated that phagocytosis of monocytes-macrophages had strong effects on antibody titer and bacteria shedding postchallenge, which could be used to predict the disease resistance in animals.

Ventilation and hypoxic ventilatory responsiveness in Chinese-Tibetan residents at 3,658 m.

When breathing ambient air at rest at 3,658 m altitude, Tibetan lifelong residents of 3,658 m ventilate as much as newcomers acclimatized to high altitude; they also ventilate more and have greater hypoxic ventilatory responses (HVRs) than do Han ("Chinese") long-term residents at 3,658 m. This suggests that Tibetan ancestry is advantageous in protecting resting ventilation levels during years of hypoxic exposure and is of interest in light of the permissive role of hypoventilation in the development of chronic mountain sickness, which is nearly absent among Tibetans. The existence of individuals with mixed Tibetan-Chinese ancestry (Han-Tibetans) residing at 3,658 m affords an opportunity to test this hypothesis. Eighteen men born in Lhasa, Tibet, China (3,658 m) to Tibetan mothers and Han fathers were compared with 27 Tibetan men and 30 Han men residing at 3,658 m who were previously studied. We used the same study procedures (minute ventilation was measured with a dry-gas flowmeter during room air breathing and hyperoxia and with a 13-liter spirometer-rebreathing system during the hypoxic and hypercapnic tests). During room air breathing at 3,658 m (inspired O2 pressure = 93 Torr), Han-Tibetans resembled Tibetans in ventilation (12.1 +/- 0.6 vs. 11.5+/- 0.5 l/min BTPS, respectively) but had HVR that were blunted (63 +/- 16 vs. 121 +/- 13, respectively, for HVR shape parameter A) and declined with increasing duration of high-altitude residence. During administered hyperoxia (inspired O2 pressure = 310 Torr) at 3,658 m, the paradoxical hyperventilation previously seen in Tibetan but not Han residents at 3,658 m (11.8 +/- 0.5 vs. 10.1 +/- 0.5 l/min BTPS) was absent in these Han-Tibetans (9.8 +/- 0.6 l/min BTPS). Thus, although longer duration of high-altitude residence appears to progressively blunt HVR among Han-Tibetans born and residing at 3, 658 m, their Tibetan ancestry appears protective in their maintenance of high resting ventilation levels despite diminished chemosensitivity.

Are Tibetans better adapted?

Evidence is reviewed from our recent (1987-1991) investigations which demonstrate better high-altitude adaptation among Tibetans than in acclimatized newcomers or other lifelong high-altitude residents. Characteristics of oxygen transport contributing to the Tibetans' remarkable exercise performance are described.

Increased vital and total lung capacities in Tibetan compared to Han residents of Lhasa (3,658 m).

Larger chest dimensions and lung volumes have been reported for Andean high-altitude natives compared with sea-level residents and implicated in raising lung diffusing capacity. Studies conducted in Nepal suggested that lifelong Himalayan residents did not have enlarged chest dimensions. To determine if high-altitude Himalayans (Tibetans) had larger lung volumes than acclimatized newcomers (Han "Chinese"), we studied 38 Tibetan and 43 Han residents of Lhasa, Tibet Autonomous Region, China (elevation 3,658 m) matched for age, height, weight, and smoking history. The Tibetan compared with the Han subjects had a larger total lung capacity [6.80 +/- 0.19 (mean +/- SEM) vs 6.24 +/- 0.18 l BTPS, P less than 0.05], vital capacity (5.00 +/- 0.08 vs 4.51 +/- 0.10 1 BTPS, P less than 0.05), and tended to have a greater residual volume (1.86 +/- 0.12 vs 1.56 +/- 0.09 1 BTPS, P less than 0.06). Chest circumference was greater in the Tibetan than the Han subjects (85 +/- 1 vs 82 +/- 1 cm, P less than 0.05) and correlated with vital capacity in each group as well as in the two groups combined (r = 0.69, P less than 0.05). Han who had migrated to high altitude as children (less than or equal to 5 years old, n = 6) compared to Han adult migrants (greater than or equal to 18 years old, n = 26) were shorter but had similar lung volumes and capacities when normalized for body size. The Tibetans' vital capacity and total lung capacity in relation to body size were similar to values reported previously for lifelong residents of high altitude in South and North America. Thus, Tibetans, like North and South American high-altitude residents, have larger lung volumes. This may be important for raising lung diffusing capacity and preserving arterial oxygen saturation during exercise.

Decreased ventilation and hypoxic ventilatory responsiveness are not reversed by naloxone in Lhasa residents with chronic mountain sickness.

Persons with chronic mountain sickness (CMS) hypoventilate and are more hypoxemic than normal individuals, but the cause of the hypoventilation is unclear. Studies of 14 patients with CMS and 11 healthy age-matched control subjects residing in Lhasa, Tibet, China (3,658 m) were conducted to test the hypothesis that hypoventilation, blunted hypoxic ventilatory responsiveness (HVR), and hypoxic ventilatory depression of CMS were due to increased endogenous opioid production. Patients with CMS compared with control subjects exhibited hypoventilation (end-tidal carbon dioxide pressure [PETCO2] = 36.6 +/- 1.0 versus 31.5 +/- 0.5 mm Hg, p less than 0.05), lower tidal volume (VT = 0.54 +/- 0.02 versus 0.61 +/- 0.02 ml BTPS, p less than 0.05), blunted HVR (shape parameter A = 17 +/- 8 versus 114 +/- 22 mm Hg/L BTPS/min, p less than 0.05), and a depressant effect of ambient hypoxia on ventilation (delta PETCO2 with acute hyperoxia = -3.5 +/- 0.5 versus -1.0 +/- 0.6 mm Hg, p less than 0.05). Reduced forced expiratory volume in 1 s to vital capacity ratios (FEV1/VC) and a higher proportion of cigarette smokers in the group of patients with CMS compared with control subjects suggested that at least some patients with CMS had mild airway obstructive lung disease. Naloxone infusion (0.14 mg/kg) to six patients with CMS did not change resting VT, PETCO2, HVR, or SaO2.(ABSTRACT TRUNCATED AT 250 WORDS)